Vibrator

ABSTRACT

A pneumatic vibrator for foundry molding machines and the like has a plunger reciprocable in a bore between striking and exhaust positions. The plunger has exhaust passage means therethrough for exhausting air from an inlet port to an exhaust port in its exhaust position. A striker insert of low sound transmitting material is positioned adjacent the inlet port. Inlet passage means passes air from the inlet port to the vibrator bore through the insert for cooling the same. Noise muffler means covers the exhaust port for reducing noise and preventing entry of foreign material into the vibrator bore.

Umted States Patent 1191 1111 3,917,233

Blower Nov. 4, 1975 VIBRATOR 3,132,704 5/1964 Bassinger 91/234 x [75]Inventor: warren A. Blower, Brecksvine, 3,718,318 2/1973 Blower259/1310. 43 x Ohlo Primary Examiner-Harvey C. Homsby [73] Assignee: TheSherwin-Williams Company, Assi nt Examiner-Alan Cantor Cleveland, OhioAttorney, Agent, or Firm-Donnelly, Maky, Renner & Otto [57] ABSTRACT Apneumatic vibrator for foundry molding machines and the like has aplunger reciprocable in a bore between striking and exhaust positions.The plunger has exhaust passage means therethrough for exhausting air Ifrom an inlet port to an exhaust port in its exhaust po- 7 11 Claims, 3Drawing Figures c A I 50 56 12 2s 16 as 411K416 52 so 54 14 54 70 18U.S. Patent Nov. 4, 1975 A 50 Th W VIBRATOR BACKGROUND OF THE INVENTIONThis application relates to vibrators, and more particularly topneumatic vibrators for use on foundry molding machines and the like.

Vibrators are commonly used in foundry molding for enhancing sand flowor assisting removal of molds from patterns or flasks. Such vibratorsmay be used on foundry molding tables, pattern stools, match plates,hoppers and like parts. The vibrators are usually double-acting and havea sleeve member. A plunger reciprocates within the sleeve betweenopposite striker plugs. In vibrators of this type, extensive machiningof circumferential grooves and ports is required in the sleeve memberand plunger. This makes thevibrator costly to manufacture.

Vibrators of the type described are also very noisy. Attempts to reducethe noise level have included the use of elastomeric striker inserts.Repeated striking of the plunger against such striker inserts producesinternal friction in the striker insert and they become extremely hot.The inserts then soften and deteriorate very rapidly requiring frequentreplacement or reconditioning of the vibrator.

With vibrators of the type described, the exhaust ports are normallyopen directly to atmosphere. Particles of sand or other foreign materialoften enter the sleeve through these open exhaust ports and interferewith movement of the plunger. The exhaust ports are also a source ofconsiderable noise. The present invention thus includes severalimprovements over prior vibrators such as shown in US. Pat No. 3,718,318dated Feb. 27, 1973 to Warren A. Blower and Emil P. Jerse.

SUMMARY OF THE INVENTION A pneumatic vibrator of the type describedincludes a housing or sleeve having a cylindrical bore therein. A

as long as air pressure is supplied to produce high frequency impacts.

In accordance with an important aspect of the invention, the exhaustpassage is formed in the plunger itself. In one arrangement, the borehas a circumferential groove therein located intermediate the inlet andexhaust ports. The groove is covered by the plunger in its strikingposition. Movement of the plunger away from its striking position opensthe groove to communication with the inlet port. The exhaust passage inthe plunger is also opened to communication with the groove. Thus, airis exhausted from the inlet port to the exhaust port through the groovein the bore and through the ex haust passage in the plunger. The exhaustpassage may include a plurality of radially extending bores in theplunger communicating with an axial plunger bore which also communicateswith the exhaust port.

In accordance with another aspect of the invention, the vibratorincludes a striker insert positioned adjacent the inlet port. Inletpassageway means passes air from the inlet port to the bore in contactwith the striker insert for carrying heat away from the striker insert.With such an arrangement, the striker insert does not become overheatedand rapid deterioration does not occur.

In accordance with another aspect of the invention, the inlet andexhaust ports are formed in end caps closing the opposite ends of thebore. The end cap in which the exhaust port is formed also includes anenlarged flared recess having noise muffler means therein covering theexhaust port. The muffler means may comprise metal mesh or wool-likematerial. A fine screen is positioned in the recess to hold the mufflerover the exhaust port. The muffler and screen prevent foreign particlesfrom entering the bore through the exhaust port. The muffler alsosubstantially reduces the noise of air escaping through the exhaustport. The noise produced by the plunger acting against the strikerinsert is also muffled.

It is a principal object of the present invention to provide an improvedpneumatic vibrator.

It is another object of the present invention to provide a pneumaticvibrator having a very low noise level.

It is a furtherobject of the present invention to pro vide a pneumaticvibrator having a cooling arrangement for preventing deterioration of astriker insert.

It is an additional object of the present invention to provide apneumatic vibrator with a muffler for reducing noise and preventingentry of foreign particles into the vibrator bore.

It is also an object of the present invention to provide an improvedsingle-acting pneumatic vibrator.

It is a further object of the present invention to provide a pneumaticvibrator 'having exhaust passage means in the vibrator plunger itself.

BRIEF DESCRIPTION OF THE DRAWING The invention may take form in certainparts and arrangements of parts, certain preferred embodiments of whichwill be-described in detail in this specification and illustrated in theaccompanying drawing which forms a part hereof.

FIG. 1 is a cross-sectional elevational view of an improved vibratorconstructed in accordance with the present invention;

FIG. 2 is a cross-sectional elevational view of another improvedvibrator constructed in accordance with the present invention; and

FIG. 3 is a cross-sectional elevational view of still another improvedvibrator constructed in accordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawing,wherein the showings are for purposes of illustrating preferredembodiments of the invention only and not for purposes of limiting same,FIG. 1 shows a pneumatically operated vibrator A including a part 12having a cylindrical bore 14 therethrough. A generally cylindricalplunger B is reciprocatingly positioned within bore 14. The opposite endportions of the internal peripheral wall forming bore 14 are internallythreaded as at 16 and 18 for threadably receiving threaded portions 20and 22 of end caps C and D. End cap C has a hole 24 thereother device.This is an end mounting type of mounting for vibrator A.

In accordance with one arrangement, an air inlet port 26 is formed inend cap C and communicates with bore 14 on one side of plunger B. Airinlet port 26 is preferably substantially coincidental with thelongitudinal axis of bore 14. Inlet port 26 communicates with an airinlet bore 28 adapted to be connected with a source of pressurized air.

Threaded portion of end cap C has an enlarged cylindrical recess 30therein substantially coincidental with air inlet port 26. A cylindricalstriker insert E is tightly fitted within cylindrical recess 30. Strikerinsert E is made of a material having very low sound transmittingcharacteristicsSriker insert'E may be formed of urethane, rubber, orsimilar materials. Obviously, natural rubber or other materials couldalso be used for striker insert E. Preferably, striker insert E isrelatively soft as compared with steel and has the desirablecharacteristicof low sound transmission. At the same time, strikerinsert E is relatively hard so that it will not be compressed too muchand absorb the force of plunger B. Such action would reduce the actionof the vibrator.

In one arragement, striker insert E is made of urethane rubber having adurometer hardness on the shore-A scale of around 80 to 100. A durometerhardness of 90 or above is preferred. Striker insert E may be molded tohave an exterior diameter slightly larger than the diameter ofcylindrical recess 30 and have a longitudinal slit therethrough. Thelongitudinal slit makes it possible to squeeze striker insert E toreduce its diameter for insertion within recess 30. The natural memoryand resiliency of striker insert E then causes it. to expand radiallyoutward into firm engagement with the peripheral wall of recess 30.Obviously, insert E could also be a tight fit within recess 30 withouthaving a longitudinal slit. Insert E could also be secured in recess 30by mechanical fastener means or adhesive.

Striker insert E has a centrally located cylindrical hole 34therethrough substantially coincidental with air inlet port 26. Strikerinsert E has a length sufficient to project out beyond. the terminal endof threaded portion 20 on end cap C when it is bottomed in cylindricalrecess 30.

Plunger B has a striker end 36 adapted to strike against striker insertE. Striker end 36 of plunger B preferably is circular and has a diametersubstantially the same as the diameter of striker insert E. Plunger Bhas a generally conical portion 38 sloping outward from striker end 36and intersecting a generally radially extending fiat circumferentialsurface 40. Plunger end surfaces 38 and 40 cooperate with bore 14 todefine an annular space 44 at the striker end portion of plunger B.

In accordance with one arrangement, striker insert E has at least oneradially extending notch 46 therethrough for allowing passage of airfrom hole 34 to annular space 44 so that air pressure can act uponplunger end surfaces 38 and 40, as well as against striker end 36.

Bore 1 4 hasa longitudinally elongated circumferential groove 50 formedtherein generally intermediate its opposite end portions. Groove 50 hasopposite terminal ends 52 and 54. Plunger B includes a rear end 56. Anaxial bore 58 extends into plunger B from rear end 56 to communicationwith a plurality of radially extending plunger bores 60. Radiallyextending plunger bores 60 also communicate with groove 50. A coilspring 64 bears against bottom end 66 of axial plunger bore 58 Anexhaust port 72 extends through threaded portion 22 of end cap D and issubstantially coincidental with the longitudinal axis of bore 14. Anenlarged outwardly opening flared recess 74 is formed in end cap Dsubstantially coincidental with exhaust port 72. .A noise muffler ispositioned within recess 74. Recess 74 may be filled with metal wool 76or the like to define the noise muffler. The material may also be amultilayer metal mesh. Mesh or wool-like material 76 may also be formedof natural or synthetic fibers. A fine circular screen 78 is positionedwithin recess 74 to hold muffler I material 76over exhaust port 72. Endcap D has a circumferential groove 80 therein receiving a C-ring 82 forholding screen 78 in position. The described arrangement with screen 78and muffler material 76 also prevents entry of foreign particles intobore 14 through exhaust port 72.

Coil spring 64 normally biases plunger B to the left toward its forwardstriking position as shown in FIG. 1 wherein plunger striker end 36impacts against striker insert E. Air enters through inlet port 26, hole34 and notch 46 to enter annular space 44. Air pressure in hole 34 alsoacts against plunger'striker end 36. Air pressure in annular space 44also acts against plunger. surfaces 38 and 40 to cause shifting movementof plunger B to the right in FIG.,1 toits rearward or exhaust position.The parts are preferably dimensioned so that the spacing from plungerend 56 to end cap end is substantially greater than the distance fromplunger surface 40 to circumferential groove end 52. With plunger B inits forwardmost striking position, groove 50 is covered againstcommunication with annular space 44 and inlet port 26. As plunger Bbegins moving to the right in FIG. 1 toward its rearward exhaustposition, plunger surface 40 will eventually move to the right of grooveend 52. This will establish communication between groove 50 and annularspace 44. In other words, communication is also established betweengroove 50 and inlet port 26. Air in annular space 44 is exhaustedthrough radial bores 60 and axial plunger bore 58 to exhaust port 72.The exhausting action occurs before plunger end 56 makes contact withend cap surface 70.

The generally large cavity defined by plunger axial bore 58 and aportion of bore 14 allows a substantial quantity of air to accumulateunder slight pressure for aiding spring 64 in shifting, plunger B backto the left in FIG. 1 for again striking against striker insert E andproducing vibrations. The size of groove 50 and holes 60, and the largevolume of the spring cavity defined by bore 58 and a portion of bore 14,allows rapid reduction of pressure in annular space 44. A large volumeof air is exhausted at low velocity to reduce noise. Exhaust port 72 islarger than inlet port 26 so that air will be exhausted at a lowervelocity than it flows through inlet port 26. This allows plunger B toreturn to its striking position. At the same time, exhaust port 72 issomewhat restricted so that some air pressure does build up rearwardlyof plunger B to aid spring 64 in moving plunger B forwardly to itsstriking position. This allows exhaust air to escape relatively slowlythrough exhaust port 72. Such action aids in reducing the noise producedby vibrator A. The exhausted air passes through and against end 70 ofthreaded portion 22 on end cap r muffler 76 which also aids in buildingup a slight pressure rearwardly of plunger B. A substantial pressuredrop occurs across muffler 76. Much of the energy and noise is absorbedand dissipated by muffler 76.

In the arrangement described, it will be recognized that hole 34 instriker insert E defines inlet passage means for passing air from inletport 26 into bore 14 in contact with striker insert E for coolingstriker insert E. The rapid repeated striking of striker insert E byplunger B produces internal friction in striker insert E and rapidlybuilds up heat which might cause striker insert E to deteriorate. Therapid continuous flow of cool compressed air in contact with strikerinsert E rapidly dissipates heat therefrom to prevent suchdeterioration. Expansion of air from line pressure to a lower pressurealso provides cooling action.

Making the exhaust port means in plunger B itself substantially reducesthe number of circumferential grooves and ports which must be formed inthe vibrator bore. Such an arrangement also makes it possible to utilizesome of the exhaust air pressure for aiding return of the plunger to itsstriking position. Passage of the exhaust air through the plunger alsoprovides a longer exhaust path than porting directly to atmosphere. Thislonger exhaust path makes it possible to accumulate some of the exhaustair and relatively slowly exhaust it to atmosphere in order to reducenoise.

FIG. 2 shows a slightly different embodiment wherein like parts aregiven like reference numerals and letters. In this embodiment, part 12comprises a cylindrical sleeve fitted within a cylindrical bore 90 on anintegral 1 part 92 of a foundry molding machine or the like. Sleeve 12has a length slightly less than the length of bore 90. End caps C and Dhave enlarged heads 94 and 96 which extend outward beyond sleeve 12 forengaging the ends of part 92. End caps 94 and 96 are tightened fortensioning sleeve 12. Enlarged heads 94 and 96 firmly engage against theends of part 92 around bore 90 for securely clamping sleeve 12 withinbore 90.

In the embodiment of FIG. 2, plunger B is slightly different in thataxially extending plunger bore 58 is not as deep as in the embodiment ofFIG. 1 and is coincidental with a somewhat smaller diameter bore 102which communicates with radially extending bores 60. In addition, endcap D has an enlarged cylindrical recess I04 extending inward from end70 thereof for receiving one end portion of spring 60 which bearsagainst bottom b of recess 104. The action and advantages of thevibrator of FIG. 2 are the same as those described with respect to theembodiment of FIG. 1.

FIG. 3 shows a slightly different embodiment wherein part 12 hasoutwardly extending ears 108 with holes 112 therethrough for receivingbolts to clamp the vibrator to another part. This arrangement provides aside mounting vibrator. Also in this embodiment, air inlet bore 28 isformed axially in end cap C substantially coincidental with air inletport 26 and the longitudinal axis of bore 14. This embodiment alsodiffers from the embodiment of FIG. 2 in that axial plunger bore 58 hasa length greater than the length of the corresponding bore in theembodiment of FIG. 2, and the length of bore 102 is somewhat less thanthe length of the corresponding bore in the embodiment of FIG. 2. Inother respects, the operation and advantages of the embodiment of FIG. 3are the same as those previously described.

Although the invention has been shown and described with respect tocertain preferred embodiments, it isobvious that equivalent alterationsand modifications will occur to others skilled in the art upon thereading and understanding of this specification. The present inventionincludes all such equivalent alterations and modifications, and islimited only by the scope of the claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as fol lows:

l. A pneumatic vibrator including a part having a bore therein, aplunger reciprocatingly positioned in said bore for movement betweenstriking and exhaust positions, air inlet and exhaust portscommunicating with said bore on opposite sides of said plunger, exhaustpassage means through said plunger for exhausting air from said inletport to said exhaust port in said exhaust position thereof, opposite endcaps closing said bore, said inlet port being in one of said end capsand said exhaust port being in the other of said end caps, said borehaving a longitudinal axis and said inlet and exhaust ports beingsubstantially coincidental with said axis, a striker insert of low soundtransmitting material adjacent said inlet port, and inlet passage meansfor passing air from said inlet port to said bore in contact with saidinsert for cooling said insert.

2. The vibrator of claim 1 wherein said inlet passage means comprises ahole through said insert substantially coincidental with said axis.

3. A vibrator including a housing having a cylindrical bore therein, endcaps secured to said housing closing the ends of said bore, areciprocating plunger in said bore, a sound attenuating striker insertsecured to the inside of one of said end caps, and an air inlet in saidone end cap aligned with a hole extending through said insert forcooling saidr insert with the inlet air.

4. A vibrator as set forth in claim 3 wherein said hole through saidinsert and said air inlet are axially aligned and coaxial with saidbore.

5. A vibrator as set forth in claim 3 wherein said insert is partiallyrecessed in said one end cap and projects slightly therefrom.

6. A vibrator as set forth in claim 3 wherein said insert is anelastomeric material having a durometer hardness on the shore-A scale offrom about to about 100.

7. A vibrator including a housing having a cylindrical bore therein, endcaps closing the ends of said bore, a plunger in said bore, an air inletin one of said end caps and an exhaust port in the other, spring meansurging said plunger toward said one end cap, a relatively short by-passgroove in said bore normally closed by said plunger, a longitudinallyextending exhaust passage in said plunger including a radially extendingpassage in said plunger communicating with said groove in all positionsof said plunger to exhaust air from said one end of said plunger to the"other when said plunger moves to expose said by-pass groove to said oneend.

8. A vibrator as set forth in claim 7 wherein said exhaust port issomewhat restricted to create a backpressure to assist the action ofsaid spring means.

9. A vibrator as set forth in claim 7 wherein said spring means extendsfrom said other end cap into said plunger through at least a portion ofsaid exhaust passage in said plunger.

10. A vibrator as set forth in claim 7 wherein said air soundattenuating striker insert secured to said one end inlet and saidexhaust port are axially aligned with each cap and having a holetherethrough aligned with said other and said bore. air inlet forcooling of said insert.

11. A vibrator as set forth in claim 7 including a

1. A pneumatic vibrator including a part having a bore therein, aplunger reciprocatingly positioned in said bore for movement betweenstriking and exhaust positions, air inlet and exhaust portscommunicating with said bore on opposite sides of said plunger, exhaustpassage means through said plunger for exhausting air from said inletport to said exhaust port in said exhaust position thereof, opposite endcaps closing said bore, said inlet port being in one of said end capsand said exhaust port being in the other of said end caps, said borehaving a longitudinal axis and said inlet and exhaust ports beingsubstantially coincidental with said axis, a striker insert of low soundtransmitting material adjacent said inlet port, and inlet passage meansfor passing air from said inlet port to said bore in contact with saidinsert for cooling said insert.
 2. The vibrator of claim 1 wherein saidinlet passage means comprises a hole through said insert substantiallycoincidental with said axis.
 3. A vibrator including a housing having acylindRical bore therein, end caps secured to said housing closing theends of said bore, a reciprocating plunger in said bore, a soundattenuating striker insert secured to the inside of one of said endcaps, and an air inlet in said one end cap aligned with a hole extendingthrough said insert for cooling said insert with the inlet air.
 4. Avibrator as set forth in claim 3 wherein said hole through said insertand said air inlet are axially aligned and coaxial with said bore.
 5. Avibrator as set forth in claim 3 wherein said insert is partiallyrecessed in said one end cap and projects slightly therefrom.
 6. Avibrator as set forth in claim 3 wherein said insert is an elastomericmaterial having a durometer hardness on the shore-A scale of from about80 to about
 100. 7. A vibrator including a housing having a cylindricalbore therein, end caps closing the ends of said bore, a plunger in saidbore, an air inlet in one of said end caps and an exhaust port in theother, spring means urging said plunger toward said one end cap, arelatively short by-pass groove in said bore normally closed by saidplunger, a longitudinally extending exhaust passage in said plungerincluding a radially extending passage in said plunger communicatingwith said groove in all positions of said plunger to exhaust air fromsaid one end of said plunger to the other when said plunger moves toexpose said by-pass groove to said one end.
 8. A vibrator as set forthin claim 7 wherein said exhaust port is somewhat restricted to create abackpressure to assist the action of said spring means.
 9. A vibrator asset forth in claim 7 wherein said spring means extends from said otherend cap into said plunger through at least a portion of said exhaustpassage in said plunger.
 10. A vibrator as set forth in claim 7 whereinsaid air inlet and said exhaust port are axially aligned with each otherand said bore.
 11. A vibrator as set forth in claim 7 including a soundattenuating striker insert secured to said one end cap and having a holetherethrough aligned with said air inlet for cooling of said insert.